{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "range": [
                  {
                    "fixed": "4ca8329c38b0edbc5e4d782a4e3b0cfc5cd7782e"
                  }
                ],
                "source": "REFERENCES_COMMIT"
              },
              {
                "original_tag": "v0.8.0",
                "range": [
                  {
                    "fixed": "6f9d147a018caae632be7758b42d1b6073495829"
                  }
                ],
                "source": "REFERENCES_TAG"
              }
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4ca8329c38b0edbc5e4d782a4e3b0cfc5cd7782e"
            },
            {
              "fixed": "6f9d147a018caae632be7758b42d1b6073495829"
            }
          ],
          "repo": "https://github.com/gethelio/helio",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-2c3r-q7gv-hp2m"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-346",
      "CWE-942"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/65xxx/CVE-2026-65957.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "range": [
              {
                "fixed": "0.8.0"
              }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StringRangeExpression"
          }
        ]
      },
      {
        "extracted_events": [
          {
            "range": [
              {
                "fixed": "0.8.0"
              },
              {
                "fixed": "0.8.0"
              }
            ],
            "source": "DESCRIPTION"
          }
        ]
      }
    ]
  },
  "details": "Helio is an MCP proxy that sits between AI agents and the tools they use. Prior to version 0.8.0, the dashboard sideband (default 127.0.0.1:3100) validated CORS request origins by matching the hostname against a private-network string prefix (10., 172.16.–172.31., 192.168.) rather than validating an IP address. A public DNS name such as 192.168.attacker.com, 10.evil.io, or 172.16.pwn.example also satisfies that prefix, so the proxy echoed the attacker origin in Access-Control-Allow-Origin. This issue has been patched in version 0.8.0.",
  "id": "CVE-2026-65957",
  "modified": "2026-11-14T02:31:02.141637374Z",
  "published": "2026-11-11T20:36:21.626Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/gethelio/helio/releases/tag/v0.8.0"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/65xxx/CVE-2026-65957.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/gethelio/helio/security/advisories/GHSA-2c3r-q7gv-hp2m"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-65957"
    },
    {
      "type": "FIX",
      "url": "https://github.com/gethelio/helio/commit/4ca8329c38b0edbc5e4d782a4e3b0cfc5cd7782e"
    },
    {
      "type": "FIX",
      "url": "https://github.com/gethelio/helio/pull/121"
    }
  ],
  "schema_version": "1.9.2",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Helio: Dashboard sideband CORS origin allowlist matches hostnames by prefix, admitting attacker-controlled origins in open mode"
}